Originally Posted by rotrex (Post 22061)

don't think so. I gain power with every degree advance I add.
We talk 14 deg of advance here with plenty of water/meth and 102 octane fuel on a 4 valve pent roof engine. Without water / meth I am stuck at about 10 degrees.

Why are you using racing fuel as base fuel? I use pump fuel 92 octane with the amounts of WM50 I mentioned earlie theoritically rated at 112-117octane on boost.

I map myself. I know how power develops as I advance ignition.
I also have a J&S safeguard knock control system with a display. Beside this system, knock is also easily audible in a Elise. With both I can map it right to the knock limit myself and observe changes by butt and by data logging.
Power changes are also easy to feel as the car weights less than 800kg.

I tune myself aswell and I can confirm that I have the same situation you have regarding advance and power. The "more" advance you feed it the more it pushes hard, at least 20deg over "stock" seems insanely too much. Also I run it insanely lean on boost, average of 15AFR from 1-4psi, Low 14AFR from 4-16psi, High 13AFR from 17-21psi above 6Krpm

Curious what ecu are you using (mine is Haltech PS1000) and if you mind throwing a picture of the plug burn?


I have build the engine with a 1mm copper shim to protect the cylinder ahead against indentation. Rover K heads tend to turn soft over time in high power mid engined applications, especially around the exhaust valve area. This is caused by insufficient coolant flow at idle and low revs after a high load situation.The MLS head gasket seals with a very sharp edge against the hardened alloy cylinder head.
I installed a electric water pump and controller to manage the heat in low rev and idle situations. Works a treat.

Thing with the shim is that I forgot to chamfer the lower edge of the cylinder bore of the shim. I had specified the shim with a inner bore diameter of 80mm, same a cylinder bore diameter to distribute forces uniformly. the firer ring has a diameter of about 83mm. Normally the shim also has a bore of 83mm. This puts the lower edge of the shim in the quench zone near the head gasket seal area.
I believe this exposed edge together with the reduced squish is responsible for the tendency to knock.
To fix this I need to replace the head gasket with a N-series head gasket, it employs a flat seal area with a larger surface, and remove the shim. that's it. Compression will still be a reasonable 9.2:1.
It is a full day of work. I just don't have the time or motivation to do it in the moment as the car is plenty fast as is.

https://youtu.be/onYUHH0muNc?t=25
To put it in perspective: The yellow Elise in front of me is powered by a supercharged Honda K20A2 engine from a Civic Type R with 280HP. On the Radiation straight I just left in it 5th gear.

Originally Posted by rotrex (Post 22065)

In Germany we use RON ratings for fuel. MOst stations sell 98 RON (94 US) Octane as the highest, but ARAL/BP sell 102 Octane fuel almost everywhere for 6 cents extra a liter.
102 Octane RON corresponds to a US 98. I use no race fuel. It is just a special pump fuel. Shells offers a 100 Octane, too It is regular pump stuff over here.
Stock timing of this engine naturally aspirated is more in the range of 30 to 32 deg ignition advance.
The ECU I use is a Emerald K3 from the UK connected to a STACK wideband lambda meter.
I run closed loop fueling at all times, even under boost.

I have to look for plug pictures, but they have more of a "tan" compared to yours.
Tried. An AFR of 13 with 0.6 bars of boost. Worked well, but increased thermal load on track.At 0.8 bar running leaner just makes it more prone to knock and I have to pull timing and I lose power.

Originally Posted by Flr Power (Post 22068)

parmas, Why do you run it so lean?
You are missing some power by running it so lean...